1. Field of the Invention
The present invention relates to an exposure apparatus and an exposure method. Particularly, the present invention can be preferably applied to an evanescent light exposure apparatus used for fine processing having a size on the order of 100 nm or less.
2. Description of the Related Art
For a photolithographic apparatus having the limit of fine processing (at present, about 0.1 .mu.m by using a near ultraviolet laser), which is limited by the wavelength of the light used, a fine processing apparatus has recently been proposed, which uses the construction of a near-field optical microscope (referred to as an "SNOM" hereinafter) as a means for permitting fine processing of a size smaller than that provided by the wavelength of the light used. An example of such an apparatus is an apparatus capable of locally exposing a resist by using evanescent light leaking from a fine aperture having a size on the order of 100 nm or less, beyond the processing limit, which is otherwise set by the wavelength of the light used. However, such a lithographic apparatus having the SNOM construction has a problem in that productivity is hardly improved because one processing probe is (or several processing proves are) used for fine processing.
As a method to solve this problem, a proposal has been made to provide a prism on an optical mask, with light being incident on the prism at an angle producing total reflection, to transfer a pattern of the optical mask to a resist at the same time by using evanescent light leaking from the total reflection surface (refer to Japanese Patent Laid-Open No. 8-179493).
In the batch exposure apparatus disclosed in Japanese Patent Laid-Open No. 8-179493, in which the prism is provided for exposure to evanescent light, the distance between the surfaces of the prism and the mask to the resist is thought to be preferably set to 100 nm or less. This is because the evanescent light leaking from the surfaces of the prism and the mask exponentially attenuates as the distance from the surfaces of the prism and the mask increases. However, since the surface precision or flatness of the surfaces of the prism and mask and the substrate, or the parallelism between the surfaces of the prism and mask and the substrate, etc., are limited, it is difficult to set the distance between the surfaces of the prism and mask and the resist surface to 100 nm or less over the entire surface of the prism and the mask. This produces a problem of nonuniformity in the exposed pattern, or causes a partial crushing of the resist by the surfaces of the prism and the mask.